Draft regulator



April 2, 1946. c. H. MORROW DRAFT REGULATOR 2 Sheets-Sheet 1 Filed Jan.4, 1945 V INVENTOR. CLARENCE H. MORROW F119- 3 BY #31- MM ATTYS.

April 2,1946. c, H, ow 2,397,879-

DRAFT REGULATOR Filed Jan. 4, 1945 2 Sheets-Sheet 2 I3 REE 5 I INVENTOR.

' CLARENCE H.MORROW 'ATTY s.

Patented Apr. 2, 1946 DRAFT REGULATOR Clarence H. Morrow, ShakerHeights, Ohio, as-

signor to The Hotstream Heater Company, Cleveland, Ohio, a corporationof Ohio Application January 4, 1945, Serial No. 571,238

' (Cl. ass-1) 3 Claims.

This invention relates to control devices for furnace draft regulators.

One object of the invention is to provide improved control mechanism inwhich upon a call for more heat the required increase in the fuelcombustion rate is delayed for a period which though short is longenough to make certain thatthe draft opening has actually been fullyclosed, thus reducing or preventing any possibility of ejecting smoke orfumes into the room in which the furnace is located.

Still another object is to provide improved control mechanism of thiskind in which the room thermostat itself directly controls but oneregulating motor, to-wit, that which operates or controls the draftregulating damper, but which motor also serves as a relay to producesubsequent delayed operation of the air or fuel feeding device for thepurpose of meeting the demand for change in the rate of heat supply.

Further objects of the invention in part are obvious and in part willappear more in detail I hereinafter.

Fig. 2 is a sectional elevation on approximately the line 2-2, Fig. 1,the dotted lines illustrating certain of the parts in damper-open orstand-by position;

Fig. 3 is a detail sectional view, on the line M, Fig. 2;

Fig. 4 is a view, corresponding to Fig. 1 and illustrating the damper indamper-open or standby position; and

Fig. 5 is a diagram, illustrating the control circuits.

The invention is an improvement upon that described and claimed in aprior patent to Morris W. Crew, and GeorgeA. Short, No. 2,381,437 forControl means for draft regulators, granted August 7, 1945, to whichreference may be had if desirable or necessary.

Referring to the drawings attached hereto, it represents any furnace orequivalent fuel burning device to which the invention may be applied.Said furnace is equipped with a. smoke conduit ii leading to the stackpipe l2 and provided with a, draft regulating damper l3 located in alateral pipe connection, as is usual. l4 indicates a pipe or conduit forsupplying to the combustion chamber from a feeding device It, additionalmaterial for increasing the rate of air, or liquid or gaseous fuel, or amixture of fuel and air, the feeding device III is an injector, fan orblower, but if solid fuel is employed said device will be any suitablestoker mechanism. whose rate of operation is increased or reduced instep with variations in the demand for heat, as is usual. In my case,the feeding device is driven by a suitable electric motor l6.

Draft damper l3 and its operating mechanism are of the same general formand arrangement shown in said prior referred to. The damper is providedwith an adjustable counterweight I1 and is pivoted at 18. It isconnected by a wire link is to the lower end of a latch member 20pivoted and sliding upon a screw 2| and provided at its upper end with arecess 22 and a latch lip 23, the latter cooperating with a fixedshoul-' der or abutment 24 and the former with lateral projection 25 onone arm 26 of a two-armed lever, the other arm 21 of which cooperateswith a stop pin 28 and has attached thereto one end of a biasing tensionspring 29.

Said lever is mounted upon and is driven by the final slow running shaft30 of speed reducing gearing, marked generally 3|, shown in Fig. 3, andoperated by a suitable synchronous clock motor marked generally 32. Onthe hub 33 of the two-armed lever is mounted a clip 34 in which issupported a suitable mercoid switch 35, to be later referred to.

Referring to Fig. 4, the clock motor 32 is connected on one side byconductor 36 to Li and on the other side by conductor 31, thermostaticswitch 38 and conductor 33 to L2. Thermostatic switch 38 is located inand is sensitive to variations in the temperature in the room or placeto be heated.

4|! represents a manual normally open switch, in a shunt circuit 4|around switch", by means of which the control system may be operatedmanually when desired.

Mercoid switch 35, normally open, is connected on one side by conductor42 to motor l6, and thence by conductors 43, 38 to Ll. On the other sideswitch 35 is connected by conductors M. 39 to L2.

The operation is as follows:

Fig. 4 represents the stand-by position of the parts, when the rate ofcombustion and of heat production is low or at a minimum. The feedindevice It is either operating ,at low speed or is idle and inoperative,as shown; because switch 35 is open. The draft damper'is held fully openheat production. If the additional material is and room air'thereforeenters the draft opening directly to stack. avoiding a drawai of hotgases from her to the stack and the loss of the heatcontained therein.

When the temperature in the'space being the combustion chamv as twotothreeseconds-to disengage heated, as at the thermostat 38, dropsbelow'thc critical value, there is a call for more heat, whereuponthermostatic switch 18 closes, immediately completing the circuitthrough the clock motor 32, which starts to rotate and to turn the.

shaft 30 and the two-armed lever 26, 21 connected thereto in theclockwise direction, Fig. 4, and

operation of the fuel motor I'B does not begin simultaneously withoperation of the damper motor, but at a later time, when it is certainthat the damper actually has closed.

, move it. at slow speed, to the position shown The speed reducinggearing 3! so reduces the rate of rotation of the parts that shaftrotates at the rate of one revolution per minute or even slower, so thatit takes approximately ten seconds or so for the mercoid switch 85 tomove sufficiently for the mercury therein to move to the other end ofthe tube and close the switch. This switch closing effect is consummatedwhen the mercoid tube has moved clockwise in Fig. 4 to a position alittle beyond the horizontal. When switch closes the circuit to themotor i8 is completed, whereupon the feeding device I5 is eitheroperated at a higher rate of speed or begins operation, according to-thesystem employed. In either case the rate of combustion and of theproduction of heat is increased in accordance with the demand, but theincrease has been delayed pending closing with certainty of the damper,so that no fumes or smoke are ejected into the open room.

Motor 32 is of such character as to enable it to remain energized andstalled indefinitely, without injury as the result of possible rise intemperature of the motor parts. When the demand for heat has beensatisfied, thermostatic switch 38 opens, thereby promptly deenergizingmotor 32. Thereupon spring 29 becomes effective to rotate the two-armedlever and shaft 39 in the reverse direction, but at slow speed onaccount of the retarding effect of the speed reducing gearing. Duringreturn motion of the lever the draft damper is moved to the openposition shown in Fig. 4, and mercoid switch 35 is returned to itsoriginal open position, cutting off the flow of current to motor as,which stops. Consequently the feeding device i5 stops and the rate ofcombustion and of heat production is reduced to its original value. Theparts remain in the position shown them when heat is called for,and*avoiding any. necessity of a delicate hair triggersetting, as willbe readily understood.

Other advantages of the invention'will be ap I parent to those skilledin the art.

What I claim is: 1; In combination with a'furnace, control appa ratutherefonincluding a feeder communicating with the furnace combustionchamber and adap s I ed by its operation to cause such furnace actuationas will satisfy a demand for more heat, an operating motor therefor,adraft damper for said furnace, an operator therefor movable alternatelyto stand-by and damper release positions, motor means for actuating saidoperator, thermostatic means sensitive to variations in temperature inthe space heated by said furnace and operative upon a demand for moreheat to cause actuation of said motor-means in, a manner to move theoperator from stand-by to damper release position, means renderedeffective by said operator during an early stage of its said movementfor causing movement of said damper to release tion, and means renderedeffective by said operator during a later stage of itssaid movement forcausing operation of said operating motor and feeder to thereby causesuch furnace operation as will satisfy the said demand.

2. In combination with a furnace, control apparatus therefor, includinga feeder communicating with the furnace combustion chamber and adaptedby its operation to cause such furnace actuation as will satisfy ademand for more heat, an operating motor therefor, a draft damper forsaid furnace, an operator therefor movable alternately to stand-by anddamper release positions, motor means for actuating said operator,thermostatic means sensitive to variations in temperature in the spaceheated by said furnace and operative upon a demand for more heat tocause actuation of said motor means in a manner to move the operatorfrom stand-by to damper release posisaid demand.

3. In combination with a furnace having a stack pipe provided with alateral opening and a pivoted damper for controlling said opening,control apparatus including a feeder communicating with the furnacecombustion chamber and adapted by its operation to cause such furnaceactuation as will satisfy a demand for more heat, an operating motortherefor, a damper operator movable alternately to stand-by and damperrelease positions, motor means for actuating said operator, thermostaticmeans sensitive to variations in the temperature in the space heated bythe furnace and operative upon a demand for more heat to cause operationof said motor means in a manner to move the operator from stand-by todamper release position, a latch slide having a disconnectibleconnection to said operator and a loose connection to said damper andarranged when disconnected to release the damper for prompt free motionto release position and for free swinging motion relative to said latchslide to accommodate itself to variations in stack draft, means renderedeffective by said operator during an early stage of its motion fromstand-by to damper release position for so disconnecting said latchslide from said operator, and means rendered effective by I saidoperator at a later stage of its said motion for causing operation ofsaid operating motor and feeder to thereby cause such furnace operationas will satisfy said demand.

CLARENCE H. MORROW.

